Revision flashcards
What is a complex ion?
A central metal ion or atom surrounded by coordinately bonded ligand
What is a coordinate bond?
A dative covalent bond
What is a ligand?
An atom, ion or molecule that donates at least one lone pair of electrons to a central transition metal ion forming a dative covalent bond
A ligand must have at least 1 lone pair
1 lone pair = monodentate
2 lone pairs = bidentate
More than 2 lone pairs = polydentate
What is the coordination number?
The number of coordinate bonds
6 = octahedral
4 = tetrahedral though sometimes square planar
What are the rate constant units?
mol dm-3 s-1
What is zero order?
If [A] changes and the rate stays the same, the order of reaction with respect to [A] is zero order
What is first order?
If the [A] is proportional to the rate the order of reaction is first order
What is second order?
If the rate is proportional to [A]2 the order is second order
Overall order =
The sum of orders of all reactants
What is a reducing agent?
Are themselves oxidised
Donates electrons
What is an oxidising agent?
Are themselves reduced
Accept electrons
What is a chiral carbon?
An carbon atom which has 4 different groups
If a molecule has more than one chiral centre it has more than two optical isomers
What is an enantiomer/optical isomer?
Have a chiral carbon
Non-super imposable mirror images
They rotate around plane-polarised light which only vibrates in one direction
One enantiomer rotates in the clockwise direction and the other in the anti-clockwise
What is a pharmacophore?
The part of a drug that fits into the receptor site and makes it medicinally active
What 3 things does the fit of a pharmacophore depend on?
1) Size and shape - must be complementary to the receptor site
2) Orientation - if its shows E/Z isomerism only one of the isomers will fit
3) Bond formation - functional groups in the pharmacophore will form temporary bonds which are mostly ionic interactions or intermolecular forces
– Dipole-dipole forces in pharmacophores with polar groups
H bonding in alcohols, amines or carboxylic acids
Ionic interactions - acidic and base functional groups can donate or accept protons to become changed and form electrostatic attractions
Amines
Organic derivatives of ammonia
If one of the hydrogens in NH3 are replaced with an R group you have a primary amine
Why are amines bases?
They have a lone pair which accepts electrons to form a cation
The lone pair on the nitrogen can form a dative bond with a H+ ion
Testing for amines
Test for using damp red litmus paper which turns blue
OR
A small amount of an acyl chloride which would give of white fumes of HCl gas
How can amines be neutralised?
Using an ammonium salt
What is a salt?
A chemical compound consisting of an ionic assembly of cations and anions which results in a compound with no overall net charge
What are 3 methods of preventing rusting?
Painting/coating
Oiling/greasing
Sacrificial method -
This involved placing a more reactive metal with the iron
Galvanizing - a coating of zinc
OR blocks of zinc can be bolted to the iron
Why are transition metals transition metals?
Part filled d-orbitals
What does it mean if an atom economy is high?
The higher the atom economy the more efficient the process as less waste products are produced
How do you calculate atom economy?
Mr of desired product / sum of Mr of all reactants
x 100
Assuming the yield is 100%
The number of moles in the chemical equation count
Calculating e nought
more positive - more negative
What does it mean if a molecule is chiral?
Non-super imposable mirror images
Or 4 different groups attached to a carbon atom
Electronegativity definition
The ability of an atom to attract a pair of electrons in a covalent bond
Test for phenol using sodium hydroxide
Solution turns colourless if phenol present
Saturated vs unsaturated
Saturated - no carbon carbon double bonds
Unsaturated - one or more carbon carbon double bonds
What is an electrophile?
Electron pair acceptors - attracted to areas electron rich e.g a double bond
The double bond is a nucleophile
Give the orders of radiation with increasing frequency and energy (so shorter wavelength)
Radiowaves, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays
Energy of a photon =
Planck’s constant (h) x frequency (v)
Frequency =
speed of light (c) / wavelength
New equation to find energy =
Planck’s constant (h) x speed of light (c)
/ wavelength
What is a pi bond?
What is a sigma bond?
Acid + metal
Salt and hydrogen gas
How do pd-pds arise
Due to differences in electronegativity in a covalent bond
How do id-ids arise
Due to uneven distributions of electrons that cause a temporary dipole that induces another dipole in an adjacent molecule
What is an isotope?
Same number of protons but a different number of neutrons
Describe the mechanism of heterogenous catalysis
Heterogenous adsorption of reactants
Bonds weaken and break
New bonds form
Products released from catalyst
Why would the data book value for enthalpy change differ from experimental values?
Bond enthalpies aren’t in standard state
Bond enthalpy values are averages
Formation of ozone (5 steps)
Formation of oxygen atoms from dissociation of water by UV
O + O -> O2 formed by photosynthesis
O2 + O -> O3
Ozone is decomposed O3 -> O2 + O
Absorbs UV from sunlight
Why do dyes absorb light
Electrons in the extended delocalised system move to higher energy levels
E=hv
Cation and anion charges
Cation positive
Anion negative
What is a salt bridge made of?
Filter paper
Potassium nitrate
Atomic emission spectrum question
Electrons are excited and move to higher energy levels
Electrons drop energy levels emitting a photon of light
E=hv
Frequency of energy emitted is proportional to gaps between energy levels
Why is an element more reactive or difference in melting point
More delocalised electrons
So attracts electrons more strongly/greater attraction for electrons
Equilibrium 6 marker
Increase/decrease in pressure
The effect on the rate
Which side has fewer moles?
More frequent collisions would increase the rate of reaction
A catalyst would increase the rate of reaction by providing an alternative route of lower Ea though would have no effect on equilibrium position
Is the reaction exo or endo? - so which side would be favoured?
What is an electrophile?
An electron deficient chemical species which accepts a lone pair of electrons to form a covalent bond
Ligands and colours
Ligands affect splitting of d sub shells
Electrons excited to a higher energy level
Specific frequency of visible light absorbed
E=hv
Transmit complementary colour
